The northern desert has vegetation only after rare rainfalls. The savanna includes a vast variety of herbaceous vegetation, with such trees as bastard mahogany, kapok, baobab, and the shea tree (karité). There are antelope, lion, waterbuck, leopard, hyena, monkey, wart hog, and countless varieties of bird and insect life. In the Niger River are crocodiles, hippopotamuses, and sometimes manatee. Turtles, lizards, pythons, horned vipers, and other varieties of snakes abound.